The present invention relates to image processing and, particularly, to a method and apparatus for correcting large defects in digital images.
Digitized images are used extensively in modern society to facilitate the communication of information and ideas through pictures. Print and film photos, documents and the like are often digitized to produce a digital image that can then be viewed, communicated, enhanced, modified, printed or stored. The increasing use of digital images has led to a rising demand for improved systems and methods for the digitization of images.
Digitized images often include imperfections that are not present in the original image. One cause of such defects is the components of the image capturing system. For example, in a scanner, the scanning surface, or platen, may contain scratches and other optical path obstructions. These optical path obstructions are digitized along with the image and appear as imperfections in the digitized image. Another cause of imperfections is defects within the physical medium of the image. For example, a photograph, film negative, or other physical medium may be scratched or deformed despite careful handling. In addition, dust, hair, smudges, and the like may be deposited on the surface of the physical medium and will be digitized along with the image. These objects will also appear in the digitized image as imperfections in the digitized image.
One method for correcting defects in the image involves the use of a defect map, wherein each pixel has a defect value proportional to the severity of the defect in the pixel. Each pixel is corrected based on its own defect value. This is generally accomplished by dividing-out the defect value from the pixel value. Another method for correcting defects in the image is to replace the defective pixel with a replacement value determined from the surrounding defective and non-defective pixels within a predetermined area. This interpolated value is then used to xe2x80x9cfillxe2x80x9d the defective pixel.
After such automatic image correcting systems have been run, there may remain certain large defects that conventional correction systems do not adequately correct. Such defects may, for example, be the result of a hole in the image media or a scratch that penetrates the image media layers. In these cases, there is generally insufficient data with which to reconstruct the pixel data.
Accordingly, a need has arisen in the art for a method and system for correcting large defects in digital image. The present invention provides a system and method for correcting large defects in digital images.
In accordance with one implementation, an image correction system is provided. In this implementation, the image correction system includes an image input device that operates to produce a digital image and a defect map. The defect map allows the identification of defective and non-defective regions of the digital image. A defect correction program and at least one correction routine is used to correct the defective region of the digital image. Examples of correction routines include a reference line correction routine, a fill correction routine, and an average correction routine. Examples of different types of reference lines used in reference line routines include feature lines, centerlines, contour lines, and user defined reference lines.
In another implementation, a defect correction program is provided. In this implementation, the defect correction program operates to receive a digital image and a corresponding defect map. As discussed above, the defect map identifies at least one defective region and a non-defective region of the digital image. The defect correction program then corrects the defective region using at least one correction routine.